Structural Changes in Phosphatidylserine Salts by Hydration and Addition of Calcium Ion

概要

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Hydrations and phase transitions of ammonium, sodium and potassium salts of phosphatidylserines (PS) were investigated by small-angle X-ray scattering (SAXS) and differential scanning calorimetry (DSC). The increase in long spacings for NH^+_4-PS by addition of water was slightly smaller than those for the other PS salts, implying that a small amount of water penetrated into the hydrocarbon regions. The long spacings for PS salts and water system were reduced by addition of CaCl_2. A mixture of phosphatidylcholine (PC) and PS in KCl aqueous solution gave a long spacing of 59Å, while it separated into two long spacings at 65 and 55Å in 1 mol CaCl_2 solution. This SAXS result shows that Ca^<2+> ion induces not only two dimensional, but three dimensional phase separation of the mixture of PC and PS. The phase transition temperature of the anhydrous NH^+_4-PS was lowest among those of the three PS salts, but fully hydrated NH^+_4-PS had the highest transition temperature among them.
社団法人日本物理学会の論文
1993-06-15